Bear Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bear Valley clear sky chart from 2005-11-06 to 2024-01-11.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
50%
23475
29%
74630
19%
23431
61%
23431
37%
39778

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
33%
757
21%
2646
13%
756
47%
756
23%
1558
January11th to 20thNight
35%
724
24%
2450
13%
724
52%
724
26%
1417
January21st to endNight
34%
792
27%
2574
14%
792
51%
792
23%
1562
February1st to 10thNight
35%
720
26%
2324
14%
720
52%
720
27%
1351
February11th to 20thNight
38%
700
27%
2098
18%
700
51%
700
28%
1245
February21st to endNight
35%
592
25%
1776
15%
592
49%
592
26%
1093
March1st to 10thNight
30%
720
18%
2160
9%
720
42%
720
22%
1442
March11th to 20thNight
38%
720
20%
1998
12%
720
47%
720
26%
1288
March21st to endNight
32%
792
18%
2044
7%
792
41%
792
26%
1366
April1st to 10thNight
39%
720
22%
1800
7%
720
48%
720
30%
1172
April11th to 20thNight
37%
711
25%
1779
7%
711
47%
711
33%
1112
April21st to endNight
45%
720
25%
1800
8%
720
52%
720
41%
1056
May1st to 10thNight
46%
646
26%
1726
12%
646
54%
646
41%
957
May11th to 20thNight
53%
418
30%
1480
24%
418
62%
418
41%
693
May21st to endNight
57%
388
24%
1552
21%
388
66%
388
37%
721
June1st to 10thNight
60%
360
27%
1440
27%
360
70%
360
38%
644
June11th to 20thNight
63%
360
37%
1440
34%
360
80%
360
60%
494
June21st to endNight
70%
360
35%
1440
36%
360
83%
360
60%
499
July1st to 10thNight
79%
350
36%
1400
41%
350
87%
350
74%
432
July11th to 20thNight
76%
348
36%
1392
41%
348
82%
348
61%
477
July21st to endNight
76%
499
38%
1588
34%
472
81%
472
57%
675
August1st to 10thNight
75%
573
36%
1638
25%
570
80%
570
67%
728
August11th to 20thNight
75%
712
36%
1780
19%
712
79%
712
72%
852
August21st to endNight
78%
792
42%
1980
25%
792
80%
792
77%
911
September1st to 10thNight
74%
720
45%
1800
26%
720
82%
720
80%
803
September11th to 20thNight
70%
720
44%
1824
28%
720
79%
720
69%
877
September21st to endNight
62%
720
41%
1980
27%
720
75%
720
63%
919
October1st to 10thNight
57%
720
33%
2128
24%
720
71%
720
49%
1042
October11th to 20thNight
57%
720
38%
2160
30%
720
71%
720
51%
1002
October21st to endNight
56%
792
39%
2396
30%
792
71%
792
53%
1087
November1st to 10thNight
55%
740
30%
2405
25%
740
65%
740
38%
1257
November11th to 20thNight
48%
760
32%
2470
21%
760
64%
760
37%
1271
November21st to endNight
39%
760
31%
2498
19%
760
55%
760
32%
1336
December1st to 10thNight
37%
760
25%
2660
13%
760
54%
760
26%
1502
December11th to 20thNight
35%
760
21%
3227
14%
759
49%
759
16%
2161
December21st to endNight
29%
829
16%
4777
13%
817
45%
817
11%
2776

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
6%7%23323346%60%
74754
Night
6%8%23323346%59%
74954
TransparencyDay
26%49%19%25%17%
74465
Night
27%5%8%19%25%16%
74765
SeeingDay
15%19%34%21%8%2
13993
Night
12%10%24%32%18%3
23490

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
11%12%3342445%7%44%
1519
11th to 20thDay
8%11%33333347%53%
1520
21st to endDay
8%15%6%5%324348%43%
1782
February1st to 10thDay
9%12%4432345%6%49%
1634
11th to 20thDay
6%12%5%5%323347%50%
1750
21st to endDay
8%13%7%8%43334444%
1480
March1st to 10thDay
8%16%7%8%434446%35%
1800
11th to 20thDay
9%18%5%5%43445%7%38%
1961
21st to endDay
8%17%5%5%434446%40%
2311
April1st to 10thDay
8%12%4433436%7%46%
2160
11th to 20thDay
9%12%43424445%50%
2129
21st to endDay
8%9%23323447%55%
2160
May1st to 10thDay
7%8%33322347%57%
2232
11th to 20thDay
7%9%24423347%56%
2409
21st to endDay
9%9%2442445%6%50%
2723
June1st to 10thDay
7%5%1332435%6%60%
2520
11th to 20thDay
3312212335%75%
2520
21st to endDay
321222333476%
2520
July1st to 10thDay
111111223383%
2520
11th to 20thDay
1212113335%78%
2520
21st to endDay
2213313335%75%
2634
August1st to 10thDay
221222234477%
2289
11th to 20thDay
211222323479%
2122
21st to endDay
11221212385%
2376
September1st to 10thDay
21112223482%
2160
11th to 20thDay
4212213245%72%
2134
21st to endDay
44331223474%
1980
October1st to 10thDay
6%5%13223345%66%
1828
11th to 20thDay
6%312223335%70%
1800
21st to endDay
6%5%13323336%67%
1958
November1st to 10thDay
8%8%23324447%55%
1674
11th to 20thDay
7%6%23424445%59%
1710
21st to endDay
6%8%33324348%56%
1677
December1st to 10thDay
11%8%3422445%7%50%
1520
11th to 20thDay
14%15%47%5%34445%35%
1928
21st to endDay
7%10%45%4245%6%10%45%
2794
January1st to 10thNight
10%12%35%33435%8%45%
2646
11th to 20thNight
5%11%244345%6%7%48%
2450
21st to endNight
7%12%45%42445%6%47%
2574
February1st to 10thNight
9%11%2433335%7%50%
2324
11th to 20thNight
411%5%6%42346%8%47%
2098
21st to endNight
7%12%48%333345%49%
1776
March1st to 10thNight
7%17%6%8%323336%42%
2160
11th to 20thNight
8%13%5%44235%5%8%44%
1998
21st to endNight
7%15%5%5%423446%45%
2044
April1st to 10thNight
8%10%4443345%8%47%
1800
11th to 20thNight
7%10%34323347%53%
1779
21st to endNight
5%9%2332345%7%59%
1800
May1st to 10thNight
45%3432435%6%61%
1726
11th to 20thNight
37%3332335%8%62%
1480
21st to endNight
48%2332235%8%60%
1552
June1st to 10thNight
5%413223435%66%
1440
11th to 20thNight
121121232481%
1440
21st to endNight
321221222480%
1440
July1st to 10thNight
11111222386%
1440
11th to 20thNight
221222223379%
1440
21st to endNight
421232233473%
1681
August1st to 10thNight
221321334476%
1647
11th to 20thNight
211222233478%
1780
21st to endNight
211121112385%
1980
September1st to 10thNight
111121111387%
1800
11th to 20thNight
2211222235%79%
1824
21st to endNight
2312322235%76%
1980
October1st to 10thNight
5%41231234471%
2128
11th to 20thNight
4313213336%71%
2160
21st to endNight
5%411212336%72%
2396
November1st to 10thNight
8%8%22323347%58%
2405
11th to 20thNight
6%6%1232445%8%59%
2470
21st to endNight
6%8%33423447%57%
2498
December1st to 10thNight
12%9%3342445%6%50%
2660
11th to 20thNight
13%18%343245%5%7%36%
3276
21st to endNight
6%11%5%6%5%45%5%5%9%38%
4862

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
39%7%11%21%17%6%
1519
11th to 20thDay
34%49%19%21%13%
1520
21st to endDay
42%5%8%15%20%9%
1782
February1st to 10thDay
37%410%18%19%12%
1634
11th to 20thDay
36%49%21%22%9%
1760
21st to endDay
45%46%19%20%6%
1480
March1st to 10thDay
50%5%9%16%15%5%
1800
11th to 20thDay
45%5%11%18%16%6%
1961
21st to endDay
46%6%14%20%11%3
2311
April1st to 10thDay
38%6%14%19%18%5%
2160
11th to 20thDay
36%5%12%23%17%6%
2132
21st to endDay
29%6%16%27%18%3
2160
May1st to 10thDay
26%5%13%29%21%5%
2232
11th to 20thDay
30%412%28%22%4
2412
21st to endDay
33%7%12%26%18%4
2724
June1st to 10thDay
24%6%11%24%27%8%
2520
11th to 20thDay
14%38%26%33%16%
2520
21st to endDay
12%36%15%35%29%
2520
July1st to 10thDay
7%2412%29%46%
2451
11th to 20thDay
10%46%15%26%41%
2445
21st to endDay
13%28%11%27%39%
2488
August1st to 10thDay
12%26%13%26%41%
2273
11th to 20thDay
10%16%11%37%35%
2122
21st to endDay
8%1412%39%36%
2376
September1st to 10thDay
9%2412%34%39%
2160
11th to 20thDay
15%37%22%34%19%
2134
21st to endDay
17%25%21%37%19%
1980
October1st to 10thDay
21%47%16%29%23%
1828
11th to 20thDay
18%37%23%28%21%
1800
21st to endDay
20%38%20%31%19%
1958
November1st to 10thDay
30%5%9%19%23%13%
1674
11th to 20thDay
27%411%19%28%12%
1710
21st to endDay
29%49%19%27%13%
1677
December1st to 10thDay
33%6%9%19%21%13%
1520
11th to 20thDay
52%46%14%14%9%
1928
21st to endDay
34%8%13%21%17%7%
2794
January1st to 10thNight
37%5%10%23%18%7%
2646
11th to 20thNight
34%6%8%16%22%13%
2450
21st to endNight
39%47%15%22%13%
2574
February1st to 10thNight
35%48%18%20%14%
2324
11th to 20thNight
33%6%9%21%21%10%
2099
21st to endNight
39%38%22%20%7%
1776
March1st to 10thNight
45%5%9%15%19%6%
2160
11th to 20thNight
39%6%10%19%18%8%
1998
21st to endNight
39%7%13%22%15%5%
2044
April1st to 10thNight
35%8%13%21%18%5%
1800
11th to 20thNight
31%6%13%22%20%7%
1779
21st to endNight
26%6%13%34%17%4
1800
May1st to 10thNight
23%6%12%29%25%5%
1726
11th to 20thNight
21%413%32%25%5%
1480
21st to endNight
23%5%16%31%20%5%
1552
June1st to 10thNight
21%6%11%24%30%9%
1440
11th to 20thNight
9%38%28%33%19%
1440
21st to endNight
11%2417%35%31%
1440
July1st to 10thNight
6%2411%33%44%
1400
11th to 20thNight
11%26%14%26%41%
1392
21st to endNight
16%25%10%28%39%
1588
August1st to 10thNight
13%26%16%26%38%
1638
11th to 20thNight
10%3413%35%35%
1780
21st to endNight
9%1213%36%38%
1980
September1st to 10thNight
6%2410%37%41%
1800
11th to 20thNight
10%45%23%36%21%
1824
21st to endNight
13%36%23%35%21%
1980
October1st to 10thNight
18%46%19%31%21%
2128
11th to 20thNight
16%46%20%33%22%
2160
21st to endNight
15%38%20%35%19%
2396
November1st to 10thNight
26%48%21%25%16%
2405
11th to 20thNight
24%5%8%21%29%12%
2470
21st to endNight
29%46%21%25%14%
2498
December1st to 10thNight
34%5%8%18%21%14%
2660
11th to 20thNight
48%6%7%13%19%8%
3276
21st to endNight
41%7%11%16%18%7%
4862

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
36%20%23%16%4
180
11th to 20thDay
25%18%28%20%9%2
240
21st to endDay
22%19%27%20%10%1
374
February1st to 10thDay
28%18%27%18%7%1
346
11th to 20thDay
23%25%28%18%6%
415
21st to endDay
24%25%33%14%3
346
March1st to 10thDay
30%27%26%12%41
420
11th to 20thDay
28%23%26%15%7%1
420
21st to endDay
27%27%29%14%3
462
April1st to 10thDay
22%26%32%14%6%
420
11th to 20thDay
29%23%30%13%4
412
21st to endDay
16%24%31%21%7%2
420
May1st to 10thDay
18%25%32%16%8%1
423
11th to 20thDay
19%23%29%18%9%1
448
21st to endDay
19%17%28%25%8%3
485
June1st to 10thDay
12%19%36%20%9%3
450
11th to 20thDay
12%20%41%18%7%2
450
21st to endDay
5%16%42%25%9%3
450
July1st to 10thDay
317%48%21%9%2
446
11th to 20thDay
210%49%26%10%3
444
21st to endDay
211%45%27%11%5%
487
August1st to 10thDay
319%43%22%10%3
447
11th to 20thDay
313%44%23%11%4
437
21st to endDay
310%48%25%12%2
495
September1st to 10thDay
312%45%28%11%1
450
11th to 20thDay
10%18%36%29%5%2
450
21st to endDay
9%15%39%30%5%2
450
October1st to 10thDay
8%21%32%30%7%2
450
11th to 20thDay
10%14%36%27%11%2
450
21st to endDay
13%17%29%27%11%3
473
November1st to 10thDay
19%15%21%25%15%4
270
11th to 20thDay
15%14%30%26%12%4
270
21st to endDay
14%19%29%25%11%1
255
December1st to 10thDay
22%16%27%16%13%6%
180
11th to 20thDay
19%28%25%14%12%1
180
21st to endDay
27%19%24%20%8%2
198
January1st to 10thNight
21%16%25%20%14%5%
760
11th to 20thNight
15%14%33%27%9%3
724
21st to endNight
18%16%27%23%13%2
792
February1st to 10thNight
20%12%28%24%13%2
720
11th to 20thNight
16%16%25%26%14%3
704
21st to endNight
22%14%25%27%10%2
592
March1st to 10thNight
24%14%27%23%10%2
720
11th to 20thNight
19%14%25%23%18%2
720
21st to endNight
18%15%29%26%10%1
792
April1st to 10thNight
16%12%29%32%11%2
720
11th to 20thNight
14%16%28%27%12%3
711
21st to endNight
11%11%30%28%17%3
720
May1st to 10thNight
9%12%28%31%17%3
646
11th to 20thNight
7%9%25%38%20%2
418
21st to endNight
9%6%23%31%28%2
389
June1st to 10thNight
8%5%24%37%25%2
360
11th to 20thNight
35%26%43%23%1
360
21st to endNight
3321%46%26%2
360
July1st to 10thNight
115%48%33%2
350
11th to 20thNight
2116%45%33%2
348
21st to endNight
3113%36%40%6%
499
August1st to 10thNight
3116%47%31%2
573
11th to 20thNight
1119%48%27%4
712
21st to endNight
2215%50%28%3
792
September1st to 10thNight
2318%46%28%3
720
11th to 20thNight
3322%39%27%6%
720
21st to endNight
46%25%34%26%5%
720
October1st to 10thNight
8%8%23%37%20%3
720
11th to 20thNight
8%9%22%38%19%4
720
21st to endNight
10%9%23%29%22%7%
792
November1st to 10thNight
13%9%21%35%18%4
740
11th to 20thNight
11%13%26%32%14%4
760
21st to endNight
13%15%28%27%14%3
760
December1st to 10thNight
21%11%28%26%10%4
760
11th to 20thNight
22%14%26%25%11%2
760
21st to endNight
23%17%26%26%7%1
836
Page generated at 2024-01-08 08:14:20. Version ac07

Copyright 2024 Attilla Danko


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